The present invention relates to apparatus for making and transporting paper sheets or the like. More particularly, the invention relates to improvements in apparatus wherein a running web of paper, foil or a like flexible material is converted into a series of successive discrete sheets which can be transported to a stacking or another processing station.
It is well known to cause a running web of paper or the like to pass through the nip of two rotary drum-shaped knife holders forming part of a cross cutter which serves to subdivide the web into discrete sheets. Such sheets are positively engaged and entrained downstream of the nip for the purpose of advancing them to the next processing station. For example, the sheet transporting means can comprise an intercepting device (also called catcher assembly) having an upper section or conveyor unit and a lower section or conveyor unit, and each such section can employ one or more endless bands, chains, belts or like conveyors which positively engage and advance successive sheets in a direction away from the nip of the knife holders. It is also known to provide such apparatus with shifting or adjusting means which can change the position of the intercepting device with reference to the cross cutter. The peripheral speed of knives at the peripheries of the knife holders is supposed to match the speed of forward movement of the running web, at least during those stages of each revolution of the knife holders when two cooperating knives approach the path of the web and are about to make a transverse cut which results in separation of a discrete sheet from the leader of the web.
Heretofore known apparatus of the above outlined character exhibit the drawback that the leaders of sheets whose material exhibits a tendency to curl are likely to advance at random in different directions so that they cannot be readily located and engaged by the conveyors of the intercepting device. The tendency of the leaders of sheets which are made of relatively thin foil, paper or other flexible material to curl or to undergo other types of undesirable deformation immediately downstream of the nip of the knife holders in the cross cutter is attributable to a number of factors, such as the generation of air currents when the knife holders are rotated at an elevated speed, the tendency of the leaders to adhere to the peripheral surface of the one or the other knife holder, the "memory" of the running web (i.e., its tendency to form convolutions due to the fact that the web is normally drawn off a reel or bobbin wherein the web is stored in convoluted form), the weight of the leader of the web and/or others. As a rule, the leader of the web and the leaders of the sheets tend to curl downwardly about an axis extending at right angles to the direction of lengthwise movement of the web. The attendant in charge of the apparatus is often required to spend a considerable amount of time in connection with adjustments of the position of the intercepting device so that the latter can properly accept successive sheets and that such sheets are properly engaged and advanced by the conveyor units of the intercepting device. The problem is aggravated when such apparatus are used in modern high-speed production lines wherein the web is driven at a very high speed and wherein the sheets should be properly transported within a rather wide range of speeds. Production lines which employ a cross cutter and an intercepting device downstream of the nip of knife holders in the cross cutter can be used for the making of steno pads, exercise books and analogous stationery products.